Quote:
Originally Posted by assasinator
i have already mentioned that the coyote has 37mm valves and 39mm are standard oversize replacements. what you dont know about 4 valve heads is low lift flow.
you guys are accustomed to high lift values to make power. 4V heads get their flow from .1-.4 lift.
ford uses standard 37mm valves in the coyote. FRPP 39mm stainless valves have back cut heads, undercut stems, and swirl polishing for 12 cfm per valve extra flow. just in valves there is ~25cfm per port over stock. that is a fact you can check out easily at the frpp site. we are talking 380 cfm for 11$ a valve. IF the stock CFM is really 355 like the engineers say. and thats without porting. typically there is ~7 cfm to be had in a 4v head from removing the valve guide bosses. ~2 cfm from a 250 grit sand roll.
so if it will help you SS guys rest easy, teel yoursleves there is NOTHING left in the heads, but the reality is, there is at least ~34cfm.
 |
No doubt the 5.0 heads are excellent.
Don't kid yourself if you believe the LS3 heads are far from optimal as well. Leave the stock valve size alone, do a good port job and you have some really nice gains.
If you want to start talking cams and cost we can roll down that road too.
500WHP LS3 N/A is very achievable and will cost much less than the 5.0. That is fact.